About Us

JSI works to find and implement practical and lasting solutions to often seemingly unsolvable problems. By offering innovative, clear, and context-specific consulting services, we work in the spirit of Dr. John Snow and hope to continue the work he began many decades ago.

Dr. Snow is frequently referred to as the ‘father of public health.’ In 1854 a cholera epidemic raged across Europe. The onset of the disease is sudden and death can result in as little as a week. In London, one devastating outbreak claimed the lives of more than 500 people in just ten days. The search for the cure and the cause was furious and fruitless.

Dr. Snow had observed cholera first-hand in 1831 as an apprentice surgeon, but it was only 17 years later, in 1848-1849, that he developed a new theory for the mechanism of cholera transmission. Contrary to the prevailing belief, Snow argued that cholera was a disease of the gut and that the causal agent must enter through the mouth and then multiply within the gut of the sufferer, subsequently spreading to others. Dr. Snow reasoned that broad transmission of cholera had to be due to contaminated drinking water.

Broad Street water pumpLondon

In September 1854, when Dr. Snow was called on to examine the causes of the cholera epidemic, he turned immediately to the water supply. His previous research suggested that the localized nature of the outbreak would mean that the cause had to be a contaminated pump or well, rather than a problem with the general water supply. He discovered that while there were five water pumps in the neighborhood, most of the deaths took place near the pump on Broad Street. Upon further investigation he discovered that among the deaths of people situated farther from the Broad Street pump, half of the deceased preferred the water from the Broad Street pump to their nearer pump, and another third attended school near the ill-fated pump. Upon presentation of his findings to community leaders, the handle of the Broad Street pump was removed, and the epidemic quickly abated. Further investigation of the well discovered that a sewer pipe underground was leaking raw sewage into the drinking water of the Broad Street pump.

Dr. Snow realized that a spot map illustrating the location of the deaths in the Broad Street cholera outbreak would be a useful addition to his report. Snow’s famous map was first exhibited at a meeting of the Epidemiological Society of London in December 1854.